Electrical control equipment



INVENTOR Filed Dec. 8, 1952 C R HODGSON ETAL ELECTRICAL CONTROL EQUIPMENT Jig. 2

Feb. 11, 1936.

Patented Feb. 11, 1936 PATENT OFFICE ELECTRICAL CONTROL EQUIPMENT Charles R. Hodgson, Atlanta. Ga... and Harry H. Knowles, Birmingham, and George N. Lemmon,

Hammad A Application December 8. 1332,.Serial No- 646,278

4 Claims.

The purpose of our invention isto provide. a means to open or close a circuit at will :with no delay, and to open the circuit automatically in case the power supply ceases for a predetermined 5- time interval, but to keep the circuit closed if the power supply ceases momentarily but comes back before the predetermined time interval has elapsed.

Referring to the drawing. Fig. 1 shows in small scale one of the devices in its box; Fig. 2 shows in larger scale the general appearance of the mechanism with the box removed; Fig. 3 is a similar view of some of the working parts in different positions than shown in Fig. 2. Fig. 4 is a partial 5 cross-section through the cover on the line AA;

and Fig. 5 is a diagram of the electrical connections for one method of using the device.

The mechanism includes a box I, with a cover 2 in which are mounted two push-buttons 3 and I0 4. Wires enter the box through the conduit 5.

Inside the box is a removable base plate 6 upon which a revolvable induction disc I is mounted, one bearing being inthe base 6 and one in the extended arm 8. The induction disc 1 passes be- :5 tween the terminals of the electromagnet 9,

where the alternating current in the coil III creates an A. C. magnetic field, causing the disc I to tend to revolve as shown by the arrow. This is the well-known induction disc action such as is i0 often used in electric meters. The bearing 3' and the corresponding bearing in the plate 6 receive the ends of the pinion. shaft which is the center of I. The teeth on this pinion are engaged by the teeth of the movable. plate II, which is pivot- FTI ally connected by the links I2, I2 to the rockerarm I3. A compressed spring l4 biases the am I2, I2 and the plate II towards the extended position, and stops limit their range of travel. The rocker-arm I3 is movable about the pivot I5, and

it carries the mercury switch I6, which is held to the arm by suitable clips. The switch has two projections H where the terminals are located, and the circuit through the switch is opened or closed as the bath of mercury I8 is rocked back 5 and forth by motion of the arm I3. Leads as shown connect the terminals to the block I9.

Pivoted to 8 is the member 20, 2|, 22, which is limited in its travel by the arm 2I and suitable stops. The face 20 is operable to press against I I and disengage the teeth of II from the pinion of I, while leaving II, I2 and I3 free to be raised or lowered, as II slides easily over the face 20. The arm 22 is engageable by arm 23 which is mounted on the pivot 25 inside the cover 2, as

shown in Fig. 4.

The parts 3, 4, 23 and 24 are all attached to the cover. 2, and areincluded in Fig. 2 in order to show their relative positions. When the button 4 is pushed inwardly against the arm 24, it rotates 25 and also 23, thereby moving 22 so that 2Il-pushes 5 I I away from the pinion shaft of I and I3 drops by gravity until stopped by the pin 34, as shown in Fig. 3. The various parts are so proportioned that, if the teeth on I I are engaged with the pinion of I, the mercury closes the switch-contacts I1; and if H is below the position of ement with the pinion of I, then the mercury-switch is open.

Secured to the plate 6 is an extended arm 28 at the outer end of which is a pivot shaft carrying the arms 21 and 28. The arm 21 is engaged by the button 3 and rotates the arm 28 which extends inwardly and engages with the arm 29 on I3. When the button 3 is pushed in 21 and 23 rotate, 23 engages with 29 and lifts I3 up from its position in Fig. 3 until the upper teeth on I I engage with the teeth on the pinion of I. When the teeth touch, further motion of I3 causes the spring I4 to be compressed as the links I2, I2 rock around their pivots, thereby bringing I I closer to I3 and allowing the teeth on I I to slip past those on the pinion. In efl'ect, the member I I acts like a ratchet with many teeth.

When the pressure on 3 and I3 is released, II is extended into proper engagement with the pin- 30 ion, where it is held by the spring I4 and the stop as shown in Fig. 2.

Meanwhile the mercury switch has closed its contacts and, as shown in Fig. 5, this bridge current from the incoming lines 30, 3| to the coil III. Thereupon, following well-known principles, the induction disc I begins to revolve, and so the teeth on the pinion lift the member I I upwards until it reaches the limit of its travel. This limit can be varied by moving the adjusting screw 32 up or down. Since the mercury-switch maintains closed contact over a considerable range of motion, there is quite a wide range of adjustment possible without opening the mercury-switch contacts.

So long as power is maintained on the line 30,

3 I, the electromagnet will keep a slight torque on I and the switch will remain closed. Whenever power goes oil the line, Ill releases its torque on I, which then revolves backwards under the weight of I3 and its associated parts. If power stays ofl, II lowers until all its teeth disengage from the pinion, whereupon the mercury switch drops to the fully open position and remains open until manually reclosed, for the mercury switch opens 46 Instead of using the weight of the mercury switch teeth, whereupon ll, I3, l6 and their associated parts all drop to the open position as shown in Fig. 3.

The distance which the rack has to drop down before it becomes disengaged from the pinion of I, varies the time interval between the instant power goes off the line and the time the circuit is opened by the mercury-switch. The adjustment screw 32 thus provides a means to alter this time interval as desired. If a still longer interval is required, a fixed magnet 33 is placed so that the disc revolves between its poles and so is retarded in its turning.

There are manyvariations which can be made.

to open the circuit when power goes off the line, the mercury switch can be held in a stationary position by a latch which is released by another weight which is'similarly lowered by the reverse motion of the disc. Other variations can also be'made without departing from the fundamental idea of this invention.

We claim:

1. Electrical control equipment which cornprises an electromagnet operating an induction disc which is connected by gearing to a mercuryswitch, together with means to disconnect the gearing if the electro-magnet becomes de-energized for longer than a predetermined time.

2. Electrical control equipment which comprises an electromagnet operating an induction disc which is connected by gearing to a mercuryswitch, and means to disconnect the gearing if the electromagnet becomes de-energized for longer than a predetermined time, together with means to disconnect or reconnect the gearing at will. I

3. Electrical control equipment which comprises a mercury-switch, an electromagnet operating an induction disc, and control means operable by the induction disc to operate the mercuryswitch once only if the electromagnet becomes deenergized for longer than a predetermined time.

4. Electrical control equipment which comprises a mercury-switch, an electro-magnet operating an induction disc, and control means operable by the induction disc to operate the mercuryswitch if the electromagnet becomes de-energized for longer than a predetermined time, together with means to operate the mercury-switch without movement of the induction disc.

CHARLES R. HODGSON. HARRY H. KNOWLES. GEORGE N. LEMMON. 

